American Goldfinch

As I sit on the backyard deck, watching the thistle feeder hanging within the protection of our Austrian pines, American goldfinches, Spinus tristis, keep this feeder busy most of the day.  Finches have the most vegetarian diet of any North American songbird.  Their favorite feeder foods include thistle and hulled black-oil sunflower seeds.

In the wild, they prefer tree and shrub seeds, and other soft plant parts including buds, berries, and sap.  All parts provide fiber, nutrients, and a good source of water.  During summer, they may incorporate small insects where insect species are abundant, but depend upon seeds for the majority of their nutritional requirements. 

American goldfinches are sexually dimorphic, with different coloration between males and females.  In late spring, preceding their breeding season, they have a unique pre-alternate molt that brightens the colors for both males and females.  During the breeding season, males are bright lemon yellow with black caps, black wings, and white wing bars.  Breeding females are an overall olive green with black wings and white wing bars.  They molt again before winter and colors for both sexes become more cinnamon and duller in appearance.

Nest sites are selected by the female, who also builds the nest in a crotch of branches well protected by overhanging leaves.  Two to seven pale blue eggs are laid and incubated by the female for 12 to 14 days.  Males bring food back for the female every one to two hours during incubation and for another two to three weeks after the nestlings hatch.  Four to five days after hatching, the male will also begin to feed the nestlings, who are now able to create their own body heat, allowing the female to leave the nest for short periods.  Parents continue to feed the young for another month before the young leave the nest.

American goldfinches are rarely troubled by cowbirds, a brood parasite that lays its eggs in other species’ nests.  Goldfinch nestlings are fed a sticky, regurgitated mass of seeds with a few insects.  This food mixture does not contain enough protein for the young cowbirds to survive.

American goldfinches are gregarious singers, vocalizing a variety of unique songs while feeding, eating, and in flight.  Monogamous pairs, males and females will sing identical songs to each other while in flight.  This strengthens the pair bonding and helps them identify each other.  Males defend the territory around the female rather than around the nest.  Squabbling males are an indication that one has gotten too close to the other’s mate.

A group of finches is known as a “charm,” from the Middle English word “cherm” referring to a blended singing of birds or children.  Some plants to include in your gardens to attract these fun, musical companions include coneflower, coreopsis, catmint, sunflowers, black-eyed Susan, and goldenrod.  Grasses, cattails, and spider silk are readily used to line their nests for comfort.